Sheet feeding apparatus

ABSTRACT

A stack of sheets, in particular hinged-lid blanks B for cigarette packets, are disposed in a vertical stack S from the top of which successive sheets are lifted by a suction member and removed by mechanical means, e.g. by a pair of conveyors 21 provided with pushers 23. 
     The suction member may be a gang of sleeves 14 to which suction is continuously supplied, so that when a sheet B is engaged by the sleeves they are lifted automatically by suction in readiness for the pushers 23 to remove the raised sheet B, after which the sleeves again drop by gravity. The stack S may be inched around a J-shaped stack, or lifted by a pair of divergent conveyors 30 to which replenishing groups of blanks G are fed from underneath.

SHEET FEEDING APPARATUS

This invention relates to feeding of sheets from a stack, for exampleblanks which are to be formed into packets such as hinged-lid packets.

In machines for packing cigarettes in hinged-lid packets it is usual tohave the supply of packet blanks held in a vertical stack and to removethe blanks singly from the bottom of the stack at the rate which packetsare being formed. Commonly such removal is performed by a reciprocatingplunger having rubber pads to which suction is selectively applied, theremaining blanks in the stack being held back by fixed ledges at theexit of the stack.

A fault which may often occur in such an arrangement is that either theplunger fails to remove the blank from the stack or, alternatively, thatmore than one blank is removed, which can cause serious disruption inthe subsequent parts of the packing machine. It may be possible toremedy this fault for a while by adjusting the fixed ledges at the exitof the stack. However, a change in level of the stack or a change in thebatch of blanks may frequently cause a recurrence of the fault, usuallyrequiring further adjustment of the ledges.

A further disadvantage in the above arrangement is the noise causedespecially at high speed, due to sudden release of the high suction fromthe suction pads; and also the flicking noise caused by the forcefulremoving of the blanks from the ledges.

According to this invention there is provided apparatus for removingsheets singly from a stack of sheets, in particular hinged-lid blanksfor cigarette packets, comprising feed means for feeding the stack withits upper end exposed in an upward direction, a substantially verticallyreciprocable suction member engageable with each successive topmostsheet at said upper end to lift the sheet clear of the other sheets inthe stack, and withdrawal means for withdrawing each sheet transverselyfrom the suction member while in its lifted position.

The means for feeding the stack may comprise a roller engageable withone side of the stack and a conveyor belt disposed along a semi-circularpath and engageable with the other side of the stack of sheets, in sucha manner that the stack is rotated about an angle of 180°, thus enablingfurther batches of sheets to be replenished above an inlet between theroller and the belt. Alternatively, the means for feeding may comprise apair of conveyors disposed at opposite sides of the stack and havingcorresponding stack supporting members which are disengageable from thestack as the stack is fed upwards.

The suction member may comprise at least one vertically slidable sleeveand a source of suction in continuous communication with the sleeve, sothat when the sleeve has been closed off by engagement with the topmostsheet the sleeve and sheet will be lifted by the suction, and when thesleeve has been reopened by transverse removal of the sheet by thewithdrawal means the sleeve will again drop under the effect of gravity.

The invention will now be described, by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 is a side view of apparatus in accordance with the invention,

FIG. 2 is a plan view corresponding to FIG. 1, but drawn to a smallerscale,

FIG. 3 is a side view of a modification of a part of FIG. 1, and

FIG. 4 is a plan view of the modification of FIG. 3.

Referring first to FIG. 1, there is shown a stack of blanks S disposedin the shape of the letter J. Blanks are supplied periodically in bulkat the right-hand limb of the J, and are removed singly from the shorterleft-hand limb. Between these limbs the blanks are rotated through anangle of 180° by means of an inner roller 1 and an outer conveyor belt 2passing around fixed pulleys 3 and 4 and adjustable pulleys 5 and 6. Inthe longer supply limb the blanks are loosely constrained by guide walls7, and they are then lightly compressed, by approximately 1 mm, betweenthe roller 1 and the band 2, which are each provided with a compressiblerubber surface. In the shorter outlet limb, to the left as viewed inFIG. 1, the blanks are again loosely constrained between walls 8.

An elongated slot 11 is formed in each of the walls 8 to which a sourceof compressed air is connected via air pipes 12. Immediately above thepipes 12 are a pair of photoelectric cells 13a and b, positioned at theoutlet of the stack.

Disposed above the top of the stack are three suction sleeves 14, bestseen in FIG. 2. The sleeves 14 are vertically slidable in a housing 15and are mechanically interconnected to a spindle 16 passing through eachof the sleeves. The ends of the spindle 16 are mounted on a pair of arms17, which are pivoted at 18 about a fixed structure and biaseddownwardly by a compression spring 19 acting on each arm 17.

Connected to the housing 15, and in communication with the sleeves 14,is a relatively large suction pipe 20 whose remote end is connected to asource of light vacuum, for example a fan.

Disposed at each side of the sleeves 14 is a conveyor 21 passing aroundthe pulleys 22, and mounted on each conveyor are a series of equi-spacedpusher members 23 which are L-shaped, as viewed in FIG. 1.

In operation, with the arms 17 in their lower position (shownchain-dotted in FIG. 1), the continuous suction applied to the sleeves14 causes the topmost blank B to adhere to the sleeves. As the bottomsof the sleeves 14 are now closed off by the blank B, atmosphericpressure acts on the underside of the blank to lift up the sleeves withthe blank. Thus the arms 17 are raised against the bias of the springs19, and the blank B is brought from the lower position to the upperposition shown in FIG. 1 in full lines. The sleeves 14 continue to moveslightly higher than the position shown, bringing the blank B intoengagement with abutments 24 formed on the housing 15, so reducing thesuction on the blank. The timing of the conveyor belt 21 is such that atthis moment the pushers 23 come into engagement with the rear corners ofthe blank B and move it horizontally away from the sleeves 14 towardsthe left (beyond which the blank is folded and processed to form apacket, in a manner well known).

When the blank B has cleared the sleeves 14, they descend again bygravity and assisted by the action of the spring 19, and proceed toremove the next blank. After several blanks have been removed from thetop of the stack the level of the stack will have dropped below apredetermined level sensed by the photoelectric cells 13a and b. Thecell 13a is electrically connected to the drive for the belt 2, and thecell 13b is similarly connected to the drive for the roller 1; and whenthe cells sense that the level of blanks has fallen to thispredetermined level, they respectively actuate the drives to the belt 2and to the roller 1, causing the whole J-shaped stack to be inchedaround, thus restoring the level at the outlet of the stack to thatshown in FIG. 1.

Compressed air to the pipes 12 may be supplied continuously in order toencourage separation of the blanks one from another.

Referring now to FIGS. 3 and 4, there is shown an alternativearrangement for inching the blanks upwards. In place of the roller 1 andbelt 2, a pair of conveyors 30 are disposed at opposite sides of a stackS'. Mounted on each conveyor are four equi-spaced supporting lugs 31a tod which are in turn engageable with the bottom of the stack. Theconveyors 30 diverge outwardly in an upward direction, so that as theyintermittently inch the stack of blanks upwards each pair of supportinglugs (e.g. in the position shown, lugs 31c) progressively move away fromthe stack.

Disposed at right angles across and between the bottom ends of theconveyors 30 is a horizontal conveyor 32 on which are carried groups ofblanks G of a predetermined height, slightly less than the spacingbetween adjacent lugs 31a to d. When a pair of lugs 31b are about toreach the position shown in FIG. 3 a new group of blanks G is fed by theconveyor 32 underneath the stack S' so that the lugs 31b are able toengage under it. As the lugs 31b carry the group G upwards, the lugs 31cin front move away from the stack S', which then drops a small amount onto the group G.

The indexing movement of the conveyor 32 may be geared to movement ofthe conveyors 30, so that as each pair of lugs reach the position oflugs 31c the conveyor 32 feeds the next group of blanks into positionunder the stack S'.

We claim:
 1. Apparatus for removing sheets singly from a stack of aplurality of sheets, in particular hinged-lid blanks for cigarettepackets; comprising feed means for feeding the stack with its upper endexposed in an upward direction, said feed means comprising a pair ofconveyors disposed at opposite sides of said stack, each having aplurality of corresponding stack supporting members which aredisengageable from said stack as said stack is fed upwardly; asubstantially vertically reciprocable suction member engageable witheach successive topmost sheet at said upper end to lift said sheet clearof the other sheets in said stack; and withdrawal means for withdrawingeach sheet transversely from said suction member while in its liftedposition.
 2. Apparatus as claimed in claim 1 in which said withdrawalmeans comprises a pair of conveyors disposed at opposite sides of thesuction member, a series of equispaced pusher members mounted on eachconveyor, and means for driving the conveyors in timed relationship withmovement of the suction member so that a pusher member from eachconveyor engages and transversely withdraws a lifted sheet.
 3. Apparatusas claimed in claim 1 further comprising replenishment means for feedinga group of sheets between adjacent stack supporting members under saidstack.
 4. Apparatus as claimed in any one of claims 1, 2 or 3 in whichsaid suction member comprises at least one vertically slidable sleeveand a source of suction in continuous communication with the sleeve, sothat when the sleeve has been closed off by engagement with the topmostsheet the sleeve and sheet will be lifted by the suction, and when thesleeve has been reopened by transverse removal of the sheet by thewithdrawal means the sleeve will again drop under the effect of gravity.5. Apparatus for removing sheets singly from a stack of a plurality ofsheets, in particular hinged-lid blanks for cigarette packets,comprising feed means for feeding said stack along a substantiallysemicircular path terminating in an upward direction with the upper endof said stack at the terminal end of said path exposed in an upwarddirection; said feed means comprising a roller engageable with one sideof said stack and a conveyor belt disposed along a substantiallysemicircular path parallel to said path of said stack and engageablewith the side of said stack opposite said one side thereof to conveysaid stack about an angle of about 180° along said path; a substantiallyvertically reciprocable suction member engageable with each successivetopmost sheet at said upper end to lift said sheet clear of the othersheets in said stack; and withdrawal means for withdrawing each sheettransversely from said suction member while in its lifted position. 6.Apparatus as claimed in claim 5 in which said withdrawal means comprisesa pair of conveyors disposed at opposite sides of the suction member, aseries of equispaced pusher members mounted on each conveyor, and meansfor driving the conveyors in timed relationship with movement of thesuction member so that a pusher member from each conveyor engages andtransversely withdraws a lifted sheet.
 7. Apparatus as claimed in anyone of claims 7 or 8 in which said suction member comprises at least onevertically slidable sleeve and a source of suction in continuouscommunication with the sleeve, so that when the sleeve has been closedoff by engagement with the topmost sheet the sleeve and sheet will belifted by the suction, and when the sleeve has been reopened bytransverse removal of the sheet by the withdrawal means the sleeve willagain drop under the effect of gravity.